The present invention relates to a device for transporting sheet members or similar members and, more particularly, to a device for use in electrostatographic image recording equipment for retaining and transporting a sheet member such as a paper sheet or a document.
Image recording equipment of the type using an electrostatographic process may be implemented as a color copier in which toner images sequentially formed in different colors on a single photoconductive element are transferred one after another to the same position on a paper sheet and then fixed to produce a color copy, as well known in the art. In this type of color copier, a paper sheet is repetitively transported a plurality of times to an image transfer station adjoining the photoconductive element, or it is wrapped round a transfer drum located at the transfer station and rotated a plurality of times by the drum. Another type of color copier uses a plurality of photoconductive elements and forms a toner image of different color on each of the photoconductive elements at a particular timing. Specifically, the plurality of photoconductive elements are arranged side by side, and a paper sheet is sequentially transported through transfer stations each being associated with respective one of the photoconductive elements. In either one of such conventional color copiers, a paper sheet being transported through the single transfer station or sequentially through the plurality of transfer stations carries a toner image non-fixed thereon. It is impossible, therefore, to transport the paper sheet by nipping it by a transport roller pair. Furthermore, a copier, whether it be a color copier or a black-and-white or similar monochromatic copier, has a fixing device having a fixing roller in which a heater is accommodated. To prevent heat generated by the heater from deteriorating the photoconductive element, the fixing device is spaced apart by a substantial distance from the transfer station which adjoins the photoconductive element. The paper sheet carrying the non-fixed toner image is transported over such a distance.
It has been customary to transport a paper sheet carrying a non-fixed toner image by using a rotatable endless belt. Specifically, the endless belt transports the paper sheet while retaining the paper sheet face up in close contact with its surface. To transport a paper sheet or similar sheet member in this fashion, there has been used some different systems, as follows.